Generally, a defect in a semiconductor substrate may be detected using a light. The light may be irradiated to the semiconductor substrate through an aperture. A light reflected from the semiconductor substrate may be analyzed to detect the defect of the semiconductor substrate.
According to related arts, the defect may be detected using only one aperture. However, recipes for detecting defects for different regions on the semiconductor substrate may be different from each other. Therefore, in order to detect the defects in each of the regions of the semiconductor substrate, the semiconductor substrate may be scanned using the light passing through a first aperture. The semiconductor substrate may then be scanned using the light passing through a second aperture. As a result, the defects may not be accurately detected. Further, a time for detecting the defects may be long.